It's not Capitalism that is failing. It's Democracy and Government. We can't effectively identify problems and pass laws that fix them. Our society is like a runaway train and we can try and apply the brakes here and there, but everyday people don't have the power to say, "This is wrong, lets do something different." If it was just a case of rich getting richer and poor getting poorer then, yes perhaps the problem is…
Capitalism's issues are not just the rich getting richer and the poor getting poorer. The main issue of capitalism is distribution of power. The only ways of fixing medical insurance, college loans, gun violence is to directly oppose the power structures created by capitalism. Capitalism is not to be understood as a purely economic system, it is also a political system, as it decides how power and decisions are used and taken. Politics is not just "what the government does" or "what parties do", the shareholders of your company deciding you should be fired is also politics.
In this optic, it is more easily understood why capitalism will and does frustrate any attempt of creating true democracy. Capitalism is directly opposed to true democracy, as capitalism relies on private ownership and thus private decision, which is opposed to democratic decision. This is why when trying to establish public healthcare or regulating medical insurance, you will be opposed by the system that is capitalism, either by crashing of the stock market, adverse action by drug companies, massive lobbying, peddling of lies via mass media, and so on. Same for college loans - in order to fix the root cause issue behind college loans you will need to reduce the cost of tuition massively through either socialization of education or direct opposition to the ability of the private owner to do as they fit with their investment in order to maximize their interests (capitalism).
Gun violence is really caused by underlying sociological issues which are caused by ideology (in the sociological sense of the word), and distribution of resources. Both of those are the way they are either largely or completely because of capitalism.
Police brutality is in no small part because the role of police is diametrically opposed to the interests of most. Indeed, police almost only enforces laws that maintain wealth concentration towards the rich and have very low efficacy when dealing with theft from the common man (wage theft is by far the majority of all theft in the US, and it's not even close, yet try to call the cops on your boss short-changing you), even cases of murder show incredibly high class bias. This leads to police and justice interactions being overwhelmingly negative towards people they are biased against, such as racial minorities and poor people in general.
As for global warming, this is an obvious issue of capitalism.
And, most of all, Democracy has always been biased for the owner class and against the worker class. Read the original US constitution, for an obvious proof.